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/*

FUNCTION

        <<strspn>>---find initial match

INDEX

        strspn

ANSI_SYNOPSIS

        #include <string.h>

        size_t strspn(const char *<[s1]>, const char *<[s2]>);

TRAD_SYNOPSIS

        #include <string.h>

        size_t strspn(<[s1]>, <[s2]>)

        char *<[s1]>;

        char *<[s2]>;

DESCRIPTION

        This function computes the length of the initial segment of

        the string pointed to by <[s1]> which consists entirely of

        characters from the string pointed to by <[s2]> (excluding the

        terminating null character).

RETURNS

        <<strspn>> returns the length of the segment found.

PORTABILITY

<<strspn>> is ANSI C.

<<strspn>> requires no supporting OS subroutines.

QUICKREF

        strspn ansi pure

*/

#include <string.h>

size_t

_DEFUN (strspn, (s1, s2),

        _CONST char *s1 _AND

        _CONST char *s2)

{

  _CONST char *s = s1;

  _CONST char *c;

  while (*s1)

    {

      for (c = s2; *c; c++)

        {

          if (*s1 == *c)

            break;

        }

      if (*c == '\0')

        break;

      s1++;

    }

  return s1 - s;

}